109
FXUS63 KIWX 162321
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
721 PM EDT Thu Oct 16 2025

.KEY MESSAGES...

- Mild Friday and Saturday with highs in the 70s to low-80s by
  Saturday

- Increasing rain and thunderstorms chances Saturday afternoon
  (70-90% chance) through Sunday morning.

- Breezy this weekend with wind gusts near 30 mph, perhaps as
  great as 40 mph at the lakeshore Sunday.

&&

.DISCUSSION...
Issued at 232 PM EDT Thu Oct 16 2025

An upper-level ridge, currently over the Central Plains, slides east
through the remainder of the week resulting in a gradual warm up. A
weak warm front is lifting through Illinois this afternoon and this
could spark a couple of rain showers tonight along the Michigan
state line. Preexisting airmass is rather dry and the best
upper- level forcing is displaced to our west. To the west of
this ridge is a swirling area of low pressure which lifts north-
northeast and become the primary focus for this forecast
package, as its cold front approaches Saturday.

This morning`s suite of model guidance has come into better
agreement with timing and amplitude of the anticipated upper-level
low. Saturday begins dry before the chance of showers and
thunderstorms increases from west to east in the afternoon.
Instability continues to be a limiting factor for the marginal
severe weather risk. Forecast soundings reveal a stout elevated
mixed layer that guidance suggests will be overcome for the
afternoon; not quite a slam-dunk solution. But this sounding also
reveals MUCAPE of less then 200j/kg, in contrast to 0-6km shear in
excess of 30 knots, and yes, even looping low-level hodographs. NAM
forecast soundings are the most robust with MUCAPE exceeding 500
j/kg. While some ingredients are in place, how quickly we can
destabilize and whether or not Gulf Coast convection will inhibit
poleward moisture transport are elements that remain to be seen, and
will likely not show their hand until Saturday morning.

The low-level jet ramps up considerably Saturday night with some
guidance suggesting 50-knot winds at 925mb. With stratiform rain
ongoing, this jet will generally fail to mix down. However, as the
surface low departs and deepens, breezy northwest winds should
develop Sunday. Wind gusts near the lake shore could gust to 40 mph.

Sharply colder Sunday with some locations trapped in the upper-50s
as deep trough spreads over the Great Lakes. How this trough evolves
beyond Sunday is unclear, with considerable spread noted in how
cyclogenesis occurs in response to an incoming shortwave. Additional
beneficial rain fall is possible (20-40% chance).

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 722 PM EDT Thu Oct 16 2025

Increasing warm/moist air advection aloft will bring an increase
in high clouds through Friday but low levels remain dry and VFR
conditions will prevail. Surface winds will also steadily veer
to a southerly direction by Friday morning but remaining around
10 kts or less.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Brown
AVIATION...AGD